feat(FN-2943): improve auth UX, agent panel status, and task lifecycle handling

- Add settings content scroll refs and trigger scroll-to-top after successful sign-in and sign-up flows with regression coverage
- Keep task card merge timers live during active merges and add SSE support for task timing refresh
- Hoist Active Agents panel above the main list, add next-heartbeat visibility, and fix stale "Connecting..." card states
- Enforce unavailable-node scheduling guards and reset task steps when reopening tasks to triage or todo

Fusion-Task-Id: FN-2943

packages/dashboard/app/components/SettingsModal.tsx

@@ -318,6 +318,7 @@ export function SettingsModal({
 }: SettingsModalProps) {
   const { confirm } = useConfirm();
   const modalRef = useRef<HTMLDivElement>(null);
+  const settingsContentRef = useRef<HTMLDivElement>(null);
   useModalResizePersist(modalRef, true, "fusion:settings-modal-size");
   const [form, setForm] = useState<SettingsFormState>({
     maxConcurrent: 2,
@@ -789,6 +790,10 @@ export function SettingsModal({
     };
   }, [activeSection, loadAuthStatus]);
 
+  const scrollSettingsToTop = useCallback(() => {
+    settingsContentRef.current?.scrollTo({ top: 0, behavior: "smooth" });
+  }, []);
+
   const handleLogin = useCallback(async (providerId: string) => {
     setAuthActionInProgress(providerId);
     setLoginInstructions((prev) => {
@@ -828,6 +833,7 @@ export function SettingsModal({
               return next;
             });
             addToast("Login successful", "success");
+            scrollSettingsToTop();
           }
         } catch {
           // Continue polling on transient errors
@@ -845,7 +851,7 @@ export function SettingsModal({
         return next;
       });
     }
-  }, [addToast]);
+  }, [addToast, scrollSettingsToTop]);
 
   const handleLogout = useCallback(async (providerId: string) => {
     setAuthActionInProgress(providerId);
@@ -881,12 +887,13 @@ export function SettingsModal({
       });
       await loadAuthStatus();
       addToast("API key saved", "success");
+      scrollSettingsToTop();
     } catch (err) {
       setApiKeyErrors((prev) => ({ ...prev, [providerId]: getErrorMessage(err) || "Failed to save API key" }));
     } finally {
       setAuthActionInProgress(null);
     }
-  }, [apiKeyInputs, addToast, loadAuthStatus]);
+  }, [apiKeyInputs, addToast, loadAuthStatus, scrollSettingsToTop]);
 
   const handleClearApiKey = useCallback(async (providerId: string) => {
     setAuthActionInProgress(providerId);
@@ -4776,7 +4783,7 @@ export function SettingsModal({
                 );
               })}
             </nav>
-            <div className="settings-content">
+            <div className="settings-content" ref={settingsContentRef}>
               {renderSectionFields()}
             </div>
           </div>

packages/dashboard/app/components/__tests__/SettingsModal.test.tsx

@@ -13,6 +13,7 @@ const mockUpdateGlobalSettings = vi.fn();
 const mockFetchAuthStatus = vi.fn();
 const mockLoginProvider = vi.fn();
 const mockLogoutProvider = vi.fn();
+const mockSaveApiKey = vi.fn();
 const mockFetchModels = vi.fn();
 const mockTestNtfyNotification = vi.fn();
 const mockTestNotification = vi.fn();
@@ -54,6 +55,7 @@ vi.mock("../../api", () => ({
   fetchAuthStatus: (...args: unknown[]) => mockFetchAuthStatus(...args),
   loginProvider: (...args: unknown[]) => mockLoginProvider(...args),
   logoutProvider: (...args: unknown[]) => mockLogoutProvider(...args),
+  saveApiKey: (...args: unknown[]) => mockSaveApiKey(...args),
   fetchModels: (...args: unknown[]) => mockFetchModels(...args),
   testNtfyNotification: (...args: unknown[]) => mockTestNtfyNotification(...args),
   testNotification: (...args: unknown[]) => mockTestNotification(...args),
@@ -193,6 +195,7 @@ describe("SettingsModal", () => {
     mockFetchSettingsByScope.mockResolvedValue({ global: defaultSettings, project: {} });
     mockFetchAuthStatus.mockResolvedValue({ providers: [] });
     mockFetchModels.mockResolvedValue({ models: [], favoriteProviders: [], favoriteModels: [] });
+    mockSaveApiKey.mockResolvedValue(undefined);
     mockTestNotification.mockResolvedValue({ success: true });
     mockFetchBackups.mockResolvedValue({ backups: [], totalSize: 0 });
     mockFetchMemoryFiles.mockResolvedValue({
@@ -719,6 +722,71 @@ describe("SettingsModal", () => {
       expect(screen.getByTestId("auth-status-github")).toHaveTextContent("✓ Active");
       expect(screen.getByTestId("auth-status-openai")).toHaveTextContent("✗ Not connected");
     });
+
+    it("scrolls settings content to top after OAuth login succeeds", async () => {
+      const openSpy = vi.spyOn(window, "open").mockImplementation(() => null);
+      mockLoginProvider.mockResolvedValue({ url: "https://example.com/auth", instructions: "" });
+      mockFetchAuthStatus.mockResolvedValueOnce({
+        providers: [{ id: "github", name: "GitHub", authenticated: false, type: "oauth" }],
+      });
+      mockFetchAuthStatus.mockResolvedValueOnce({
+        providers: [{ id: "github", name: "GitHub", authenticated: true, type: "oauth" }],
+      });
+
+      vi.spyOn(globalThis, "setInterval").mockImplementation((callback: TimerHandler) => {
+        void Promise.resolve().then(() => {
+          if (typeof callback === "function") callback();
+        });
+        return 1 as unknown as ReturnType<typeof setInterval>;
+      });
+
+      const { container } = renderModal();
+      await waitForSettingsModalReady();
+
+      const settingsContent = container.querySelector(".settings-content") as HTMLDivElement;
+      expect(settingsContent).toBeInTheDocument();
+      const scrollToSpy = vi.fn();
+      Object.defineProperty(settingsContent, "scrollTo", {
+        value: scrollToSpy,
+        writable: true,
+      });
+
+      await userEvent.click(screen.getByRole("button", { name: "Login" }));
+
+      await waitFor(() => {
+        expect(scrollToSpy).toHaveBeenCalledWith({ top: 0, behavior: "smooth" });
+      });
+      expect(openSpy).toHaveBeenCalled();
+    });
+
+    it("scrolls settings content to top after API key save succeeds", async () => {
+      mockFetchAuthStatus.mockResolvedValueOnce({
+        providers: [{ id: "openai", name: "OpenAI", authenticated: false, type: "api_key" }],
+      });
+      mockFetchAuthStatus.mockResolvedValueOnce({
+        providers: [{ id: "openai", name: "OpenAI", authenticated: true, type: "api_key" }],
+      });
+
+      const { container } = renderModal();
+      await waitForSettingsModalReady();
+
+      const settingsContent = container.querySelector(".settings-content") as HTMLDivElement;
+      expect(settingsContent).toBeInTheDocument();
+      const scrollToSpy = vi.fn();
+      Object.defineProperty(settingsContent, "scrollTo", {
+        value: scrollToSpy,
+        writable: true,
+      });
+
+      const openAiCard = screen.getByTestId("auth-provider-icon-openai").closest(".auth-provider-card") as HTMLElement;
+      await userEvent.type(within(openAiCard).getByPlaceholderText("Enter API key"), "sk-test-key");
+      await userEvent.click(within(openAiCard).getByRole("button", { name: "Save" }));
+
+      await waitFor(() => {
+        expect(mockSaveApiKey).toHaveBeenCalledWith("openai", "sk-test-key");
+        expect(scrollToSpy).toHaveBeenCalledWith({ top: 0, behavior: "smooth" });
+      });
+    });
   });
 
   describe("Plugins section navigation", () => {